This invention generally relates to an enclosed environmental control system in which a fogging system of an agricultural animal or bird enclosure building such as a pork or poultry house is controlled solely in accordance with sensed temperatures and, more particularly, to such a control system in which both a fogging system and other temperature altering devices are controlled in accordance with conditions sensed by a single probe.
Modern poultry and pork houses have fogging systems for uniformly spraying atomized water into the house for emergency cooling of the animals. Generally, two parallel water lines extend along the sides of the house which have fog nozzles located along the lines approximately ten foot intervals. The water lines are connected to a high pressure water source through a solenoid controlled valve to maintain a pressure in the lines of 150-200 pounds per square inch, and the nozzle openings are sufficiently small to create a very fine mist. When the solenoid is actuated, the valve is opened, and when the solenoid is deactuated, the solenoid is closed to terminate fogging.
It is known to control actuation of the solenoid controlled valve in accordance with the relative humidity. In such systems, a humidistat with a humidity sensor measures the relative humidity. If the temperature exceeds a preselected limit, such as eighty-five degrees Fahrenheit, when the sensed relative humidity is less than a preselected lower limit, such as ninety percent, the humidistat actuates the solenoid controlled valve to commence fogging. Once fogging commences, the temperature will begin to drop at the approximate rate of ten degrees per hour. As the temperature decreases and the fogging system continues to operate, the relative humidity, of course, rises. It is desired to prevent undesirable excessive wetting of the house and the animals caused by misting under conditions of excessive relative humidity. Accordingly, once the sensed relative humidity exceeds a preselected upper limit, such as ninety percent, the humidistat deactuates the solenoid controlled valve to terminate further fogging regardless of temperature.
Such humidistat controls suffer from the basic disadvantage that it is difficult to maintain the humidity sensor in good working order. Pork and poultry houses are often dusty. Known humidity sensing elements become easily clogged by dirt and moisture, and consequently such sensors have an unsatisfactorily high rate of failure and inaccuracy.
In addition to provision of such fogging systems, it is also customary to provide poultry or pork houses with other means for altering the temperature, such as automatically controlled ventilation louvres like the Auto-Curtain ventilation systems made by the A. T. Newell Co. Inc., assignee of this invention. In such case, it is known to employ a separate thermostat with temperature sensor for controlling operation of such other temperature altering means. Thus, in known systems both a humidistat and a thermostat are required for environmental control in such a building.